Roundness, contamination particle and weld seam inspection on tubes
As everybody knows, toothpaste helps to give us healthy, attractive and clean teeth. But when brushing your teeth, who thinks about whether the toothpaste itself is actually clean? A tube filling machine fills and welds up to 540 tubes per minute. Despite high material quality, impurities in the form of tiny particles, deformation in the tube cross-section due to preceding working processes and, in rare cases, defective welding on the base of the tube cannot be totally ruled out. However, in order to be able to supply the customer with 100% fault-free products, the tube filling machines are equipped with machine vision systems.
The high-speed tube filling machines transport six tubes per cycle on two tracks through the machine. Three images per camera are captured per cycle. This means that high detail resolution is possible for each tube, which results in even tiny foreign particles inside the tube being reliably detected.
This inspection method calls for cameras that are robust enough to be used for a long period with the continuous loads of three-shift operation. At the same time, the cameras need to provide high performance to deal with the three image evaluations within a machine cycle. The shortest time between two images is 70 ms. The In-Sight cameras from our partner Cognex meet the specified criteria. In conjunction with adapted LED illumination, which is actuated in flash mode, this resulted in three inspection stations with two cameras each, in which the tubes are inspected for roundness, contamination and correct weld seams.
Filling a compressed tube results in contamination of the machine and causes a long stoppage for cleaning. Monitoring the roundness means that tubes that have been compressed during packaging or the feed process are not filled, thus preventing the associated stoppages. The particle and weld seam inspection prevents contaminated or not completely sealed tubes from getting into stores and thus to the consumer. These are all key arguments for toothpaste manufacturers when it comes to choosing the machine supplier.